Profound hypotension and near syncope during coronary artery spasm.
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Coronary Vasospasm↗
Biomedical subjects
M M Mower
Publications and source records attributed to M M Mower.
Spontaneous contrast visualization on the right side of the heart during echocardiography.
Microbubble contrast visualization within the right heart is almost always due to intravenous injections containing microbubbles. In the absence of immediate administration of agitated solutions, several other mechanisms for the occurrence of echo contrast spontaneously in the cardiovascular system have been postulated. Often overlooked as a source of contrast are microbubbles from remotely injected solutions that persist in the circulation because of markedly delayed clearance. Two patients were observed with apparently spontaneous contrast detected in the right heart chambers, both of whom had congestive heart failure, tricuspid regurgitation, and pulmonary hypertension. Regardless of the exact mechanism involved, the finding of this phenomenon reflects the presence of right heart failure and a low flow state.
Aged↗
[Implantable defibrillators. Clinical experience].
The clinical experience with the Automatic Implantable Cardioverter-Defibrillator (AICD) now extends to over 800 patients suffering from malignant ventricular arrhythmias, most of them survivors of sudden cardiac death. This device monitors cardiac rhythm for long periods of time, identifies ventricular fibrillation and life-threatening ventricular tachycardias, and then restores normal heart action with effective electrical discharges. The AICD practically eliminates the need for trained personnel and the time constraints associated with conventional out-of-hospital resuscitation, significantly decreasing the arrhythmic and total mortality rates of the implantees. Through August, 1985, 130 consecutive patients underwent implantation of the AICD at The Johns Hopkins Hospital in Baltimore; the one-year mortality due to arrhythmias was 1.7%. These results are similar to those reported by other centers. Thus, the growing clinical experience with the automatic implantable cardioverter-defibrillator has demonstrated a marked reduction of the mortality rate of the implantees.
Adolescent↗
Management of the prolonged QT syndrome and recurrent ventricular fibrillation with an implantable automatic cardioverter-defibrillator.
Two patients with the prolonged QT syndrome and recurrent ventricular tachyarrhythmias are presented, one of them refractory to combination antiarrhythmic drug therapy and bilateral stellate ganglion blockade. We implanted and tested in vivo an automatic cardioverter-defibrillator to provide a cardiac monitoring system with the capability of delivering a 25 J electrical discharge to the heart if rapid ventricular tachycardia or ventricular fibrillation is detected. Arrhythmia induction in the electrophysiology laboratory confirmed the appropriate recognition of the arrhythmias in each patient, with prompt discharge of the device and resultant termination of the tachycardias. We suggest that implantation of such a device may provide an effective adjunct to antiarrhythmic drug therapy in the management of infrequent, but potentially lethal, ventricular arrhythmias occurring in patients with the prolonged QT syndrome.
Adult↗
The manipulation of potassium efflux during fluoride intoxication: implications for therapy.
Based on findings in 2 fluoride-toxic patients, it was suspected that hyperkalemia played a clinically important role in the etiology of sudden death from fluoride poisoning. Using fluoridated human erythrocytes as an in vitro model, it was confirmed that fluoride produced a marked potassium efflux from intact cells. Further, neither glucose and insulin in pharmacologic doses, nor various buffers could halt the efflux by shifting the potassium intracellularly. If these results can be extrapolated to the clinical situation, removal of potassium and fluoride via exchange resins or dialysis remains the only reasonable approach to this life threatening problem. Aside from sudden hyperkalemia and hypocalcemia, no serologic marker for fluoride toxicity has been identified. A high degree of clinical suspicion is therefore essential to the diagnosis.
Calcium↗
Recent clinical experience with the automatic implantable cardioverter-defibrillator.
The automatic implantable cardioverter-defibrillator is an electronic device designed to monitor the heart continuously, identify ventricular tachycardias and ventricular fibrillation, and terminate the life-threatening arrhythmias with an internal countershock. This device has been proved to be safe and effective, and its use has led to a significant decrease of arrhythmic mortality in the implantees.
Arrhythmias, Cardiac↗
Clinical experience with the automatic implantable defibrillator.
Since February 1980, worldwide, over 400 survivors of sudden arrhythmic death have been treated with the automatic implantable defibrillator. Recently, the device has been further improved; it is now a cardioverter-defibrillator (AICD), able to treat ventricular tachycardias as well as ventricular fibrillation. There are two defibrillating electrodes which are used also for waveform analysis; one is located in the superior vena cava, the other is placed over the cardia apex. A third bipolar right ventricular electrode serves for rate counting and R-wave synchronization. When ventricular fibrillation occurs, a 25-joule pulse is delivered; when ventricular tachycardia faster than a preset rate is detected, the discharge is R-wave synchronized. Special batteries can deliver over 100 shocks or provide a three-year monitoring life. Implantation of the device can be achieved through a thoracotomy or by a subxiphoid or a subcostal approach. Thus far, the longest follow-up period has been 58 months. Actuarial analysis shows the one-year mortality attributed to arrhythmias reduced to less than 2%. Thus, the automatic cardioverter-defibrillator can reliably identify and correct potentially lethal ventricular tachyarrhythmias, leading to a substantial increase in survival in properly selected high-risk patients.
Death, Sudden↗
The treatment of malignant ventricular arrhythmias with combined endocardial resection and implantation of the automatic defibrillator: preliminary report.
Fourteen patients with refractory ventricular tachyarrhythmias were treated with combined endocardial resection and implantation of the automatic defibrillator. There were 11 men and 3 women with a mean age of 53 years (range, 41 to 58 years). All patients had coronary artery disease; the mean ejection fraction was 26%, and the mean number of cardiac arrests was 2.6. Programmed electrical stimulation induced sustained ventricular tachycardia in 13 patients and nonsustained ventricular tachycardia in 1. Operative endocardial mapping in the 13 patients with sustained ventricular tachycardia demonstrated a septal focus of early activation in 9 patients and a nonseptal site in 4. Following resection, sustained ventricular tachycardia could not be reinduced. There was 1 operative death. Programmed electrical stimulation performed one month after operation induced ventricular tachycardia in 5 patients, but tachycardia could not be induced in the other 8 survivors. The longest follow-up was 32 months; the average was 17 months. There were 2 late deaths. One patient died of myocardial infarction and 1 of pulmonary edema following a routine cholecystectomy. In another patient, late ventricular tachycardia developed but was automatically terminated by the implanted defibrillator. These results suggest that endocardial resection combined with implantation of the automatic defibrillator may offer the greatest protection yet available to patients with malignant ventricular tachyarrhythmias.
Adult↗
Pathophysiology of ventricular tachyarrhythmias amenable to electric control.
Technical advances now permit permanent implantation of devices such as antitachycardia pacemakers, cardioverters and cardioverter-defibrillators for control of ventricular tachyarrhythmias. Despite the fact that these devices have been implanted only in patients resistant to conventional medical and surgical management, their effectiveness has been very encouraging. While improved designs are anticipated, preliminary studies have clearly indicated that one of the major challenges for successful clinical use will be appropriate interfacing of the device with the pathophysiology of the patient. Failure to recognize this fact will likely lead to unsuccessful clinical application. Moreover, these new instruments appear to be complementary to, rather than a replacement for, existing medical and surgical approaches to the patient with life-threatening ventricular tachyarrhythmias.
Anti-Arrhythmia Agents↗
The automatic implantable cardioverter-defibrillator.
The automatic implantable cardioverter-defibrillator is an electronic device designed to monitor the heart continuously, to identify malignant ventricular tachyarrhythmias, and then to deliver effective countershock to restore normal rhythm. There are two defibrillating electrodes which are also used for waveform analysis; one is located in the superior vena cava, the other is placed over the cardiac apex. A third bipolar right ventricular electrode serves for rate counting and R-wave synchronization. When ventricular fibrillation occurs, a 25 joule pulse is delivered; when ventricular tachycardia faster than a preset rate is detected, the discharge is R-wave synchronized. The device can recycle three times if required. Special batteries can deliver over 100 shocks or provide a 3-year monitoring life. Implantation of the device is made either through a thoracotomy or by a subxiphoid approach. Thus far, the device has been implanted in 160 patients with a follow-up of 42 months. Acceleration of ventricular tachycardia to a faster rhythm or to ventricular fibrillation occurred only rarely and is dealt with most successfully through recycling. Actuarial analysis of the initial 52 patients has indicated 22.9% one-year total mortality, a 52% decrease from the 48% mortality that would be expected in the same group of patients without the device; the mortality attributed to arrhythmias was only 8.5%. In conclusion, the automatic cardioverter-defibrillator can reliably identify and correct potentially lethal ventricular tachyarrhythmias, leading to a substantial increase in survival in properly selected high-risk patients.
Death, Sudden↗
Twiddler's syndrome: a new twist.
Twiddler's syndrome, characterized by dislodgment of pacemaker leads due to twisting of pulse generators within the subcutaneous pocket with subsequent retraction of leads and loss of pacing function, has been well described in patients with permanent pacemakers implanted for bradyarrhythmias. The case presented here is the first report of a patient with an internal automatic cardioverter-defibrillator with lead dislodgment due to pulse generator rotation. This case exemplifies a new subset of patients prone to the Twiddler's syndrome.
Adult↗
Automatic implantable cardioverter-defibrillator structural characteristics.
There are a number of equipment options and surgical techniques available for automatic implantable cardioverter-defibrillator implantation. The system can be successfully used even in problem cases where restrictions may be imposed because of physical build or the presence of other implanted devices. The sensing requirements and energy output of the units can be tailored to the exact needs of the particular patient. Battery life and device function are easily monitored periodically following implantation, making possible elective replacement of the pulse generator when the batteries become depleted.
Arrhythmias, Cardiac↗
Implantable cardioverter-defibrillator: patient selection and implantation protocol.
The experience obtained from the clinical trials with the automatic implantable cardioverter-defibrillator have reemphasized the need for a detailed pathophysiologic evaluation of the patient preoperatively. This evaluation requires careful documentation of the probable cause of the ventricular tachyarrhythmia and evaluation of other surgical needs of the patient, as well as consideration of the interactive effects of pacemakers and concurrent pharmacologic therapy postoperatively.
Adolescent↗
Clinical performance of the implantable cardioverter-defibrillator.
The automatic implantable cardioverter-defibrillator has been implanted in 276 patients with ventricular tachyarrhythmias refractory to therapy with a follow-up period up to 50 months (average 9.75 months). The functional performance of the device has so far been most encouraging. The risks and complications associated with its use are acceptable and quite similar to those observed in patients with implanted pacemakers. Acceleration of ventricular tachycardia to a faster rhythm or to ventricular fibrillation is dealt with successfully through recycling. Actuarial analysis indicates that the device has a significant impact on the survival rate of the implantees, reducing the one-year mortality rate attributed to arrhythmias to only 2%.
Actuarial Analysis↗
Surgical techniques for implanting the automatic implantable defibrillator.
Since February 1980, the automatic defibrillator was implanted in 77 survivors of multiple cardiac arrest. The subxiphoid technique was used in 28 patients and the thoracotomy technique was used in 20 patients with previous cardiac surgery. Median sternotomy was used in 29 patients undergoing open heart procedures as well as defibrillator implantation. While the subxiphoid is the most benign procedure employed, all are safe and well tolerated. The method used is determined by the clinical picture. Survival studies indicate improved survival in this high risk population.
Adolescent↗
Clinical experience with the implantable cardioverter-defibrillator.
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Actuarial Analysis↗
Use of the automatic implantable cardioverter-defibrillator in the treatment of malignant ventricular tachyarrhythmias.
Since February, 1980 nearly 200 automatic cardioverter - defibrillators have been implanted in patients with malignant ventricular arrhythmias. The currently-employed device weighs 298 grams and occupies a volume of 162 cm3. There are two defibrillation electrodes which also serve as sensors: one, an intravascular catheter placed in the superior vena cava at the level of the right atrium; the other, a flexible rectangular patch placed extrapericardially over the apex of the heart. Additionally, there is a bipolar right ventricular electrode for rate counting and R-wave synchronization which will eventually be used for pacing as well. The unit is powered by lithium batteries with a projected monitoring life of three years, or the capability of discharging approximately 100 times. The arrhythmia detector activates the cardioverter -defibrillator about 15 to 20 seconds after diagnosing a "treatable" arrhythmia, identified on the basis of a striking absence of isoelectric potential segments characteristic of ventricular fibrillation and many ventricular tachycardias. The diagnosis also requires fulfillment of individually-programmed heart rate criteria. If the initial discharge of 25 joules is ineffective, the device will recycle as many as three times with a final pulse of up to 42 joules. Of the twelve nonsurvivors among the initial 52 implantees who underwent implantation through September, 1982, only four deaths were unwitnessed and considered to be sudden and arrhythmic; the other eight deaths were due to heart failure or unrelated causes. Thus, from a predicted mortality of 48% in the same group of patients if the automatic defibrillator had not been implanted, the "sudden death" mortality was reduced to 8.5%.
Electrocardiography↗
Catheter defibrillation.
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Cardiac Catheterization↗